1. Field of the Invention
The present invention relates to a magazine for holding a large number of substantially flat articles, flatwise folded cartons in particular, in a stacked condition between a pair of substantially parallel guides and, more particularly, to a magazine for releasing such articles or cartons one-by-one from downstream end portions of a pair of guides after which the articles, such as cartons, can be opened using a mechanism such as a suction cup.
2. Description of Background and Pertinent Information
According to a conventional magazine of this type, for example, as disclosed in Japanese Laid-Open Patent Application No. 26833/84, a pair of inclined guides are spaced from each other by a distance less than a vertical width of each folded carton to form a restriction, thereby making it difficult for pressure on the upstream side to be applied to the cartons on the downstream side. A small detent or flap-engaging pin is provided at a discharge end portion to prevent accidental discharge of a carton located at the extreme end of the downstream side. Further, a horizontal conveyer for carrying a large quantity of cartons thereon in an upright condition is disposed on the upstream side of the lower guide, which conveyer is driven upon detection of a positional change of the upper edges of the upright cartons as the cartons are withdrawn, to supply cartons intermittently in a quantity matching the quantity of the cartons withdrawn from the magazine. By this construction, the resistance of each carton being withdrawn is minimized to permit cartons to be withdrawn relatively easily.
3. Problems to be Solved by the Invention
The conventional magazine is constructed so that the cartons contained therein are subject to approximately equal pressures from the upstream cartons and both upper and lower edges thereof come into engagement with the above restriction, allowing the cartons to slide downstream successively every time a carton located at the downstream end is withdrawn. However, since the magazine is intended to hold not only flatwise folded cartons but also flat base papers and folded leaflets, there arises the problem that the specific and unique characteristics of cartons are ignored, resulting in relatively unsatisfactory handling of cartons.
The present invention has been effected, in particular, in consideration of the properties peculiar to folded cartons.
A folded carton tends to open by virtue of the stiffness of the base paper from which it is made. The degree of expansion of a carton varies depending upon the difference in the quality or dimensional accuracy of the base paper, or the difference in the storage time in a folded state. But such folded cartons tend to open at all times. Consequently, the aforementioned restriction does not have the desired effect on all of the cartons; the pressure induced thereby may be imposed on the carton located at the downstream end; and there arises the necessity of taking some countermeasure against sudden discharge of cartons at the discharge end of the magazine.
In order to overcome the problems mentioned above, it is important to make the vertical width of each carton relatively uniform and it is necessary to limit the quality of paper and to improve the dimensional accuracy of storage standard. However, these solutions present the problem of increased material costs.
In particular, since the cartons are normally formed into containers by overlapping both edges of the original cut sheet and then securing them to each other, the positions of the overlapped, secured edges are apt to be displaced, and are apt to vary from carton to carton, and their edge-to-edge dimensions in a direction perpendicular to the direction of the folding lines of the cartons tend to be easily disturbed, resulting in that in case that both edges in a direction perpendicular to the direction of the folding lines of the cartons which are to be held between the paired guides as found in the above-mentioned prior art, it presents a problem that the cartons may easily be jammed between the the two guides and the most downstream carton may accidentally be discharged, or the force required to remove the carton may become high in order to prevent the accidental discharging operation.
The aforementioned property of each folded carton tending to open creates an expansive elasticity in the stacked direction of the cartons in the magazine. However, since such elasticity itself is not a large force, this property is utilized effectively by reducing the urging force or gravity of the succeeding cartons and the frictional resistance of the flow of cartons. That is, it is important that the carton being withdrawn convert its vertical compression into an opening action in which it tends to expand in the stacked direction at the discharge end of the magazine.
In the above-mentioned conventional magazine, an additional pressure from the upstream side is applied to a minimum extent to the carton located at the downstream end. Conversely, when cartons are pushed back from the downstream to the upstream side by a mechanism assisting in their successive release from the magazine, the cartons are further compressed so greatly that it is almost impossible to push the cartons back by such a mechanism. Further, it is difficult to open the cartons because they are withdrawn in a compressed condition.
In the foregoing description of the conventional magazine, moreover, cartons in a quantity corresponding to the quantity of the cartons withdrawn from the downstream end are replenished by driving the horizontal conveyer upon detection of a degree of tilting of the cartons which are carried upright on the horizontal conveyer. So where the row of the cartons on the horizontal conveyer for detecting the degree of tilting of the cartons is not long, it becomes difficult to effect the detection, resulting in deteriorated responsibility for control and the necessity of a wider mounting space for the magazine.